1. Field of the Invention
The field of this invention relates to tailor made amide-imide copolymers and terpolymers prepared from tricarboxylic acid anhydride derivatives, N,N'-diacylated diamines, N-acetylated diamines and diamines and to molding powders and molded articles prepared therefrom.
2. Background
Amide-imide polymers and copolymers are a relatively new class of organic compounds known for their solubility in nitrogen containing solvents when in the polyamic acid form. The major application of these amide imides has been as wire enamels. This is illustrated in U.S. Pat. Nos. 3,817,942 (1974), 3,661,832 (1972), 3,494,890 (1970) and 3,347,828 (1967). Amide-imide polymers and copolymers have also been found useful for molding application as shown in U.S. Pat. Nos. 4,016,140 (1977) and 3,573,260 (1971). Both are incorporated herein by reference. None of the foregoing references disclose tailor made amide-imide copolymers and terpolymers.
The general object of this invention is to provide tailor made injection moldable tailored linear high molecular weight amide-imide copolymers and terpolymers. A more specific object of this invention is to provide a novel process for preparing injection moldable tailored linear high molecular weight amide-imide copolymers and terpolymers by reacting acylated diamines with tricarboxylic acid anhydrides and diamines, at a temperature of about 50.degree. to 700.degree. F., wherein the imide, imide-imide, amide, amide-amide moieties incorporated into the polymer backbone are controlled by acylating the amine functionality which is to form the amide and amide-amide moieties while reacting directly those diamines with the tricarboxylic anhydride compound which are intended to form the imide and imide-imide moieties of the amide-imide copolymers and terpolymers. The molar ratio of the aromatic to aliphatic, cycloaliphatic and araliphatic diamines are suitably in the range of about 9:1 to 1:1, advantageously in the range of about 3:1 to 3:2.
In the novel process, the amide, amide-amide moieties incorporated into the polymer backbone are controlled by reacting acylated diamines with the tricarboxylic anhydride compound to form amide and amide-amide linkages and by the addition of diamines which form imide or imide-imide linkages. Advantageously these monomers are mixed in the presence of solvents such as N-methylpyrrolidone, N,N-dimethylacetamide, acetic acid, etc.. According to the process of this invention the copolymers and terpolymers may contain from two up to six different structural units set forth hereinbelow: ##STR1##
In the foregoing structural units Z is a trivalent aromatic radical. Z may be a trivalent radical of benzene, naphthalene, biphenyl, diphenyl ether, diphenyl sulfide, diphenyl sulfone, ditolyl ether, and the like.
Useful aromatic tricarboxylic acid anhydrides which contribute the trivalent radical moiety of Z include those compounds containing at least one pair of carboxyl groups in the ortho position with respect to each other or otherwise situated in a fashion which permits the formation of an anhydride structure, one other carboxyl group and from 9 to 21 carbon atoms. Within these limits, these compounds may contain one or more benzenoid rings such as, for instance, trimellitic anhydride and its isomers and multi-ring compounds such as the 1,8-anhydride of 1,3,8-tricarboxylnaphthalene. Usually these compounds contain up to three benzenoid rings. The preferred aromatic tricarboxylic acid anhydride employed in the novel process is trimellitic anhydride.
R.sub.1 is a divalent aromatic radical of six to twenty carbon atoms joined directly or containing stable linkages consisting of --S--, --O--, ##STR2## --SO.sub.2 --, --CO--, or methylene radicals. Aromatic diamines include para- and metaphenylenediamine, para- and meta-xylenediamine, oxybis (aniline), thiobis (aniline), sulfonylbis (aniline), diaminobenzophenone, methylenebis (aniline), benzidine, 1,5-diaminonaphthalene, oxybis (2-methylaniline), thiobis (2-methylaniline), and the like. Examples of other useful aromatic primary diamines are set out in U.S. Pat. No. 3,494,890 (1970) and U.S. Pat. No. 4,016,140 (1977), both incorporated herein by reference.
R.sub.2 is a divalent aliphatic, cycloaliphatic or araliphatic radical of from two to eighteen carbon atoms derived from aliphatic diamines such as ethylenediamine, propylenediamine, 2,2-dimethylpropylene diamine, tetramethylene diamine, hexamethylene diamine, octamethylene diamine, nonamethylene diamine, decamethylene diamine, dodecamethylene diamine, 4,4'-diaminodicyclohexylmethane, xylylene diamine.
Utilizing the novel process, seven different classes of amide-imide copolymers and terpolymers have been prepared. Suitably each copolymer and terpolymer is prepared utilizing both aromatic and aliphatic diamines. Usually the molar ratio of the aromatic to aliphatic diamines is in the range of 9:1 to 1:1. Advantageously, this range has been found to be 3:1 to 3:2. The copolymers and terpolymers have structural units as shown in Table I hereinbelow.
TABLE I ______________________________________ POLYMER CLASS STRUCTURAL UNITS ______________________________________ I A, B II A, C III A, B, C, D IV A, B, E V A, C, E VI A, B, C, D, E VII A, B, C, D, E, F ______________________________________
In the polymers of Classes I, II, and III the tricarboxylic acid anhydride group in the polymer is ordered head to head and tail to tail due to the order of the acylation of the diamines. The polymer of Class I is suitably prepared by diacylating of the aliphatic, cycloaliphatic or araliphatic diamine and part of the aromatic diamine. The remainder of the aromatic diamine is reacted with two equivalents of the tricarboxylic acid anhydride compound to produce a bis imide/bis acid intermediate. The reaction between the bis imide/bis acid and the diacetyl derivative of the aromatic diamine produces Structural Unit A. In a similar manner the reaction between the bis imide/bis acid and the diacetyl derivative of the aliphatic, cycloaliphatic or araliphatic diamine produces Structural Unit B. The random dispersion of structural units A and B along the copolymer and terpolymer backbone thus make up the complete structure of Polymer I. When the polymer is further polymerized under solid state polymerization conditions at a temperature of about 450.degree. to 700.degree. F. a high molecular weight injection moldable copolymer and terpolymer is obtained having inherent viscosity in the range of 0.3 to 2.0. For the purpose of this invention inherent viscosity is measured at 25.degree. C. and 0.5% w/v in 60/40 w/w phenol/1,1,2,2, tetrachloroethane. The term "solid state polymerization" refers to chain extension of polymer particles under conditions where the polymer particles retain their solid form and do not become a fluid mass.
The copolymers and terpolymers of Class II are similar to polymers of Class I, but in this instance the aliphatic, cycloaliphatic and araliphatic diamine moieties are used to form imide groups (Structural Unit C) and the aromatic diamines are used to form either two amide groups (Structural Unit A) or two imide groups (Structural Unit C). The resulting Class II copolymers and terpolymers are made up of random units A and C. Class III copolymers and terpolymers are made up of Structural Units A, B, C and D and have all the trimellitoyl groups ordered head to head and tail to tail and all diamines are allowed either to form two amide groups or two imide groups.
In copolymers and terpolymers of Class IV, V, and VI the aliphatic, cycloaliphatic and araliphatic diamines are used to form only di imide or di amide groups (Structural Units B, C, and D). Thus the trimellitoyl groups which are attached to the aliphatic or araliphatic diamines are ordered head to head or tail to tail. The aromatic diamines are acylated randomly thus some are diacylated while others are monoacylated or unacylated. The trimellitoyl groups which are attached to two aromatic diamine groups are randomly distributed between a head to head, a tail to tail, or a head to tail sequence (Structural Unit E). Polymer VI is similar to the polymers of Class V except that in polymers of Class VI the aliphatic diamines are used in both di imide or di amide formation. Polymers of Class VII are fully random in that both aliphatic diamine and aromatic diamine moieties are distributed between imide and amide portions and all trimellitoyl groups are free to be arranged head to head, tail to tail or head to tail. All of the foregoing polymers have an inherent viscosity in the range of 0.3 to 2.0 dl/g giving them molecular weights in the range of about 3,000 to 100,000. All these polymers can be injection molded and can be used as engineering plastics. They have excellent mechanical properties as shown in Table IV hereof.
With the use of Table II, a general method of preparation of these different polymers is herewith given. Polymers of structural classes I, II, III, V, and VII are prepared by first mixing and reacting the ingredients of columns J, K, and L usually in the presence of a solvent. If the acylating agent is active (e.g. an acid anhydride), reaction will occur readily at room temperature. When slow to react acylating agents (e.g. acetic acid) are used, this mixture must generally be heated to effect the proper amount of condensation. The reactants from columns P, Q, and R can be premixed, prereacted, or added separately to the prereacted mixture of J, K, and L. The solvent is removed by distillation and the mixture is polymerized under melt polycondensation conditions to yield the tailored polymer. Polymers of structural classes IV and VI are prepared by first mixing and reacting the ingredients of columns K and L, usually in the presence of a solvent. If the acylating agent is active (e.g. an acid anhydride), reaction will occur readily at room temperature. This is then followed by the addition of the ingredient from column P. After this mixture has reacted, the ingredients from columns Q and R can be added separately or in a premixed or prereacted form. When slow to react acylating agents are used (e.g. acetic acid), the mixture of K and L must generally be heated to effect the proper amount of condensation. After the addition of the ingredient from column P, a further period of heating will be required to effect the proper amount of condensation. After this mixture has reacted, the ingredients from columns Q and R can be added separately or in a premixed or prereacted form. The solvent is removed by distillation and the mixture is polymerized under melt polycondensation conditions to yield the tailored polymer. In many cases, the melt prepared polymers from all structural classes are preferably solid state polymerized prior to fabrication.
TABLE II __________________________________________________________________________ J K L P Q R MOLES OF ACYL- ATING MOLES MOLES AGENT MOLES MOLES MOLES STRUCTURAL OF OF SAME OF OF OF CLASS ArDA RDA AS TMA ArDA RDA TMA __________________________________________________________________________ ##STR3## T X ##STR4## O X II ##STR5## O X ##STR6## T X III ##STR7## M X ##STR8## T - M X IV O T X Y O X V Y O X O T X VI O M X Y T - M X VII Y T X O O X __________________________________________________________________________ Acylating Agents include Acetic Anhydride, Acid or Propionate, etc. X = total moles TMA Y = total moles ArDA T = total moles RDA X = Y + T TMA = Trimellitic Anhydride ArDA = Aromatic Diamine RDA = Aliphatic Diamine O&lt; M&lt;T&lt;Y
By way of particular example, if it is desired to produce an amide imide copolymer and terpolymer of Structural Class V wherein the ratio of aromatic to aliphatic diamines is 3 to 1 requires that X=4, Y=3 and T=1, 3 moles of the aromatic diamine are acylated with 4 moles of the acylating agent, which may be acetic acid, acetic anhydride or propionic anhydride or any aliphatic acid or anhydride which contains from 2 to 10 carbon atoms. 4 moles of trimellitic compound are mixed or reacted with 1 mole of aliphatic diamine, or added separately to the acylated diamine mixture. The mixing is conducted in the presence of solvents such as N-methylpyrrolidone, N,N-dimethylacetamide, acetic acid, etc. The organic polar solvent is removed by distillation and the mixture is polymerized under melt polymerization conditions to yield an injection moldable copolymer and terpolymer of Class V. The novel process enables one to tailor the polymerization so that different structural classes can be incorporated depending on the properties desired in the resulting product. These copolymers and terpolymers have an inherent viscosity of 0.3 to 2.0 and heat deflection temperatures greater than 350.degree. F. without the use of fillers or fiber reinforcements. Although the first stage melt polymerization products have an IV of at least 0.2 dl/gram and can be used for injection molding application, it is generally preferable to start with a copolymer having been solid state polymerized or further melt polymerized.
The solid state polymerization which can be carried out below the melting point of the polymer can be conducted in several ways. However, all of the techniques require heating the ground or pelletized copolymers and terpolymers below the polymer melting point, generally at a temperature of about 400.degree. to 550.degree. F., while either sparging with an inert gas, such as nitrogen or air, or operating under vacuum.
According to the novel process of this invention linear, high molecular weight copolymers and terpolymers have been prepared containing both aromatic and aliphatic moieties by a melt process. This in itself is a novel process feature since the prior art teaches only interfacial and solution polymerization techniques for the production of fully ordered head to head, tail to tail and completely random amide-amide polymers. Furthermore, according to the novel process a method for tailor making amide-imide copolymers and terpolymers has been disclosed. These copolymers and terpolymers have excellent mechanical and thermal properties and can be readily injection molded. This injection moldability of these polymers can be partially contributed to the fact that these polymers are linear and are not cross linked. Injection molding of the copolymers and terpolymers is accomplished by injecting the polymer into the mold maintained at a temperature of about 150.degree.-400.degree. F. In this process a 0.1-2.0 minutes cycle is used with a barrel temperature of about 425.degree. F. to 650.degree. F. The injection molding conditions are given in Table III.
TABLE III ______________________________________ Mold Temperature 150-400.degree. F. Injection Pressure 1000-40,000 psi and held for 0.5-10.0 seconds Back Pressure 0-500 psi Cycle Time 6-120 seconds Extruder: Nozzle Temperature 425.degree. F. to 650.degree. F. Barrels: Front heated to 425.degree. F. to 650.degree. F. Screw: 10-200 revolutions/minute ______________________________________
The mechanical properties of the copolymers and terpolymers prepared in Examples 1-10 are given in Table IV.
TABLE IV __________________________________________________________________________ MECHANICAL PROPERTIES OF COPOLYMERS AND TERPOLYMERS ASTM Polymer Class Method V IV VII V IV IV VII V V __________________________________________________________________________ ArDA/RDA MBA/- MBA/- MBA/- MBA/- MBA/- MPDA/- MPDA/- OBA/- OBA/- HMDA HMDA HMDA MXDA MXDA HMDA HMDA MXDA MXDA ArDA/RDA ratio 3/1 3/1 3/1 3/1 3/1 3/1 3/1 3/2 2/1 Tensile Strength, D-638 psi 17,100 13,100 18,500 19,500 9,500 15,900 13,700 18,100 21,640 Tensile Modulus, D-638 psi 360,000 361,000 363,000 408,000 405,000 437,000 450,000 472,000 488,000 Elongation at D-638 Break, % 8.2 5.5 16.9 17.1 2.9 5.3 4.1 11.7 17.1 Flexural Strength, D-790 psi 24,400 22,200 23,500 26,600 14,100 26,700 26,700 28,400 30,200 Flexural Modulus, D-790 psi 501,000 451,000 460,000 527,000 508,000 584,000 573,000 586,000 614,000 Izod Impact, ft. D-256 lb/in notch 0.46 0.38 1.99 0.38 0.36 0.36 0.33 0.42 0.63 Tensile Impact, D-1822 ft. lb/in.sup.2 56.2 32.1 72.3 120 6.5 50.7 48.0 56.9 38.3 H.D.T. @264 psi, D-648 .degree.F. 401 398 412 420 415 433 432 413 424 Density 1.29 1.29 1.29 1.30 1.30 1.35 1.35 1.33 1.34 Inherent viscosity 1.01 0.99 0.91 0.81 0.62 0.92 -- 1.26 1.41 Example # 1 5 9 6 7 4 10 2 8 __________________________________________________________________________ ArDA = Aromatic diamine RDA = Aliphatic diamine MBA = Methylenebisaniline HMDA = 1,6Hexanediamine MXDA = Metaxylylenediamine. OBA = Oxybisaniline MPDA = Metaphenylenediamine